A technique disclosed herein relates to an electro hydrostatic actuator (EHA) system which is applicable as various actuators for, e.g., an aircraft.
In recent years, from the point of improvement of fuel consumption of an aircraft and reduction of maintenance tasks of an aircraft, it has been proposed that an EHA is installed as an actuator for, e.g., a landing gear retraction/extension operation, a steering operation, a braking operation, and a fluid control operation, instead of a conventional hydraulic actuator system installed in an existing conventional aircraft (see, e.g., Japanese Patent Publication No. 2007-239974). An EHA system includes an extendable hydraulic linear actuator having a cylinder and a piston, a hydraulic pump, and an electric motor. The hydraulic pump is driven by the electric motor, thereby operating the extendable hydraulic linear actuator without a supply of oil pressure from an outside hydraulic source.